There is no conception in man's mind
which hath not at first, totally or in parts,
been begotten upon by the organs of sense.
---Thomas Hobbes, Leviathan, 1651

Thursday, September 24, 2009


I will likely be sparse in posting for a couple of weeks. My wife and I are going on vacation to the Bay area in California to visit friends and eat at some wonderful places including Bouchon (Thomas Keller), Chez Panisse (Alice Waters), a private tasting menu at Orson (Elizabeth Falkner), Calafia (Charlie Ayers), and the Mi Lupita Taco Truck in Oakland. Its hard to tell what I'm the most excited about! You can be sure you'll receive a thorough analysis from a culinary and sensory perspective when I return.

A quick note about the widgets I've got on the right side of your screen.

First, the Google Voice gadget. This actually works, and it works through your home or cell phone. What it does when you click on it is call you first and then connect you directly to my voicemail. Please give it a try!

Next, the flagged stories gadget contains interesting stories I find mainly from one of my 90+ RSS feeds I pay (varying levels of) attention to.

Lower down, I just added a Sensory Book List, where I'm going to start building a book library list of Sensory and Culinary Science books that I personally have found interesting. Email (or call!) me if you have any suggestions - the ones listed are incomplete. I'll finish the library once I get to campus in the next coupla' days.

Finally, I have a list of Sensory Science Journals. This is all of the RSS feeds that I pay attention to related to the Sensory Science field. If you click on "View all" you can actually subscribe to this list all at once for your own purposes.

Wednesday, September 16, 2009

How do you measure up?

For each of us understanding our own taste and flavor sensory response is challenging. Do you detect a hint of cardamom in that curry? Or is that cumin? Does the rice have a hint of star anise, or allspice (or both)? Do I like my hamburger medium rare or well done (and does that preference change from day to day)?

Sensory scientists are constantly asking our panelists to answer these questions, which as you can see can become very challenging because we're trying to measure a response that is already ambiguous.

Enter scaling. We've all seen them, those little surveys that are left in hotel rooms or handed to us by our server at a restaurant.  Something like ----

How much do you agree with these statements: 
The flavor of the overall meal exceeded my expectations.
My food was served hot and fresh.
The quality of the food was excellent.

And then you check off one of the following for each statement:
Strongly disagree
Somewhat disagree
Neither agree nor disagree
Somewhat agree
Strongly agree
These surveys are mostly useless for many reasons.  First and foremost, surveys should provide objective information that is actionable, but instead surveys like this are designed by managers to stroke egos. 

Lets break my simple survey down.
"The flavor of the overall meal exceeded my expectations" is leading.  It encourages us to already think about how great the meal was, rather than rate the flavor objectively.  Second, if the soup was terrible but the entree sublime, how do you answer this question?  If you rate it based on the entree, then we mistakenly think the soup was perfect. 

"My food was served hot and fresh." 
This question is asking two things.  Food can be hot and not fresh, fresh and not hot, both hot and fresh, or neither.  Again, the answer is unactionable.  Second, what does fresh mean?  Fresh from the farm?  Fresh/raw?  Fresh-not-sitting-under-a-heatlamp-for-20-minutes?  Or are they asking if the food tasted stale and old and moldy?  Not sure here, but hopefully its not the latter.

"The quality of the foods is excellent."
Besides that this is another example of a leading question, the food is excellent compared to what?  The corn chowder I hypothetically just ate was excellent compared to a low fat frozen microwavable corn chowder, but was mediocre at best compared to the chowder I had last Christmas at Ashley's in Little Rock.  And what is quality?  Microbiological quality?  Color?  Taste?  Odor?  Cooking?  It is extremely ambiguous.

The rating doesn't have enough options, either.  I hate to break it to all of you, but no matter how much time you spend trying to decide whether or not you "Slightly Agree" or "Strongly Agree" with a statement, most restaurants lump these two categories together and determine that you were simply happy. 

Finally, you can't really average this scale together, at least not legitimately (sadly I'm sure some places do).  This is because if you assign the numbers 1 to 5 to the categories you're assuming an equal interval of "agreement" or liking between the numbers.  For example, is the distance between "strongly disagree - slightly disagree" the same as "neither agree nor disagree - slightly disagree"?  Probably not for most of you.   So it doesn't make sense to say that slightly agree is twice as much agreement as slightly disagree.

So what's the answer?   Well, I will spare you the lecture in psychophysics (for now), but I assure you it involves a lunatic/genious named Gustav Fechner.a nightmare, astronomy, and the fate of your soul (or at least Fechner's).  So simply trust me that this works:

This scale, the "Labeled Affective Magnitude" (LAM Scale) was developed by Howard Schutz, a legend in the sensory community who has been publishing non-stop since around 1950.  It happens to be for liking, so you'd have to rephrase your questions in the restaurant survey, but you could do it.  What is important here is to notice the top and bottom anchor - "greatest imaginable liking."  This helps to "center" everyone on the same scale, no matter their frame of reference.   If my greatest imaginable food liking is my grandmother's Thanksgiving dinners, then this scale works, and if it is a meal cooked in the greatest restaurants in the world, it also works.  Notice that the phrases aren't evenly distributed.  That psychophysics stuff taught us how to space these things so that we CAN apply a ruler to them and average them together from different people. There's other scales (i.e. the army quartermaster 9 point hedonic scale) that also work in similar fashion.  Your tax money via the army research labs developed both of these, btw.

My backup plan is to re-design restaurant surveys, because most are truly comical.  I hope that restaurants don't give them too much weight, and now you don't either, unless of course I designed it!  

Tuesday, September 8, 2009

What is Food Science?

The CIA lecture on Texture was a resounding success. The first part was geared towards helping students understand what Food Science was and was not - for example, when I asked them to tell me what their ideas of Food Science were they responded "Biotech," "Alton Brown," and "Molecular Gastronomy." Biotechnology and genetic engineering is a subfield of a subfield of Food Science. Alton Brown does a decent job covering the pop science aspects of food science, but he is an admitted anthropologist. And Molecular Gastronomy in its current incarnation is chemistry.

The second half of the lecture was based on a post I made here called The Tactile Symphony. I spurred a lot of conversation among students and got them thinking about the truly multidimensional nature of the culinary experience.

See a summary of my lecture and grab a pdf of the presentation here:

So, what is Food Science?

Food Science is a place for anyone who has a scientific inquiry about any aspect of food, from the taste and flavor, psychology, biology, chemistry, food safety, physics, nutrition, farming, fermentation, cheese making, enology, brewing, packaging, marketing and even protein structures and genetics. A food scientist learns a little about all of these things, and learns a lot and specializes in one or two aspects.

I think it is important that in this day and age to dispel myths about a field that have become increasingly harsh-toned. Food Science has been aligned with everything that is wrong with our food system, which admittedly could use improvement, but we don't go along damning the entire field of Doctors every time one incompetent surgeon leaves a scalpel in someone's abdomen. Its just that the field itself is relatively unknown, which thus makes it easy to create misconceptions about.

Thursday, September 3, 2009

out of your mind (and into a computer)

Some of the graduates of our lab go on to do varied things, because sensory science has a number of different aspects to it.  At Penn State, John Hayes studies the genetic basis of food perception, and is knee deep in gene sequencing.  If luck goes his way, he'll be contracting with NASA to work on relieving food boredom for astronauts next year.  Another graduate of our lab, Frank R., works for Symrise using sensory methodology to study flavor compounds.  Jeanine D. earned tenure at Ohio State as their sensory professor before being lured away by Firmenich, where she is a Senior Scientist in R&D.  And my wife, Effie, is a Food Scientist developing new food products at The International Food Network and their resident sensory science expert.

My own research, as I've alluded to from before, involves methods of creating Perceptual Maps.  So what are these?

Well, perceptual maps are a visual way to show relationships between sensory stimuli, which may be flavor samples, products, odors, pictures, or even texture samples.  The maps show the mental process of categorization.  Products that are mentally similar are represented close to one another, and products that are mentally dissimilar are further apart. There are many sensory methods to create these maps, and one I've studies quite a bit is called projective mapping.  Lets look at the apple picture again.

Ignore the arrows, for a moment, and focus on the labeled points.  At the bottom, you see the GS (Granny Smith) and AM (Acey Mac) located close to each other.  In a blind taste test, these apples were represented very similar.  Because they are pretty far away from the Red Delicious (RD) we conclude that these are more dissimilar. 

The arrows represent attributes of the apples and are statistically correlated with  the juices in the general direction of the arrow.  While we may have been able to guess that the Granny Smith was tart, I had no idea that a Pink Lady and Acey Mac were related on that attribute.  The arrows also tell us that the tart apples are negatively associated with the sweet arrow  because they are opposite of the sweet arrow.  Thus, there is a sweet/tart opposing axis.  Along the horizontal, there is also a crisp/mushy opposing axis.  Our conclusion is that texture and sweetness/tartness were the primary sensory dimensions for apples based on this test and these samples! 

For this test, I peeled and cut up the apples and treated all of them with citric acid to prevent browning ("Fruit Fresh" is the commercial name).  They were placed in plastic cups, which were labeled with random three digit codes.  We used red tinted lights in the room to even out any minor color variations in the apples, so that people could focus more on taste and wouldn't use color as criteria in their categorization.   The subjects sat in front of a 60cm square sheet of white paper, and tasted the apples and physically placed them on the paper such that apples that were close to each other were similar, and apples that were further were different.   In essence, each person is building their own personal perceptual map.  Then via the magic of fancy statistics (via R, the best statistics software out there) we combine the maps into an average map for the entire set of subjects.  The attribute arrows are added by asking the subjects to write down words next to the apples that help distinguish that apple.

The uses of these maps are numerous.  Food companies use them to see where their products sits compared to competitors.  They are used in cognitive research to evaluate peoples perception before and after some sort of intervening test condition, such as behavioral therapy treatment, to see if it was effective.  Anthropologists use perceptual maps to see how different cultures view relationships among kin. 

While I did not invent this method, I do hope to come up with new methods of creating perceptual maps.  I've been reading up on Graph Theory and have some ideas already that I'll be testing in the next week or two.